When $S{O}_2$ is passed through acidified solution of $H_{2}S$:

Q. $H_{2}S$ is passed through an acidified solution of copper sulphate and a black precipitate is formed. This is due to:

Q. When SO₂ is passed through acidified K₂Cr₂O₇ solution.
(a) The solution turns green
(b) The solution is decolourized
(c) Reduction of SO₂ takes place
(d) Green ppt of Cr₂(SO₄)₃ is formed

Q. When $S{O}_2$ is passed through an acidified solution of $K_{2}C{r}_2{O}_7$, then chromium sulphate is formed. Change in oxidation state of Cr is from.

Q. When $S{O}_2$ is passed through acidified solution of potassium dichromate, then chromium sulphate is formed. The change in oxidation number of chromium is?